Towards the end of his life Sir Richard Wallace began to discuss the possibility of leaving his collections to the Nation, but was unable to secure assurance from the Government of the day with respect to running costs.

When he died in 1890 he bequeathed his entire estate to his widow, Amélie-Julie-Charlotte Castelnau (1819-1897). It was Lady Wallace who on her death in 1897 made what has been described as the greatest ever single bequest of art treasures to a Nation.

In drawing up her will in 1894, Lady Wallace was almost certainly motivated by a desire to honour the wishes of her husband whilst, at the same time, she wished to commemorate his own important role in the formation and preservation of the collection. Lady Wallace bequeathed to the British Nation the pictures and works of art "placed on the ground and first floors and in the galleries at Hertford House". She also specified that the Government should provide a site to build a new museum and that the collection should be kept together, unmixed with other objects of art, and should be styled the Wallace Collection.

The terms of Lady Wallace's bequest mean that the Wallace Collection does not acquire new works of art for its collections. Nor does it normally display works of art from other collections alongside works in the permanent collection. Visitors to the Collection are therefore able to appreciate and enjoy one of the greatest collections ever assembled, essentially in its original form.